The present invention relates generally to safety devices for engine powered implements and more particularly to such safety devices which function to promptly stop the engine or moving parts in the event that the operator leaves the operating position (deadman safety devices).
Deadman safety devices which are used in conjunction with lawn mowers, snow b1owers, garden tillers and other such power equipment having an engine which drives a potentially dangerous rotating implement often use a common interface with the operator, namely one in which the operator must continuously grip a bail handle or other lever against a spring force in order to maintain the equipment in its normal operational condition. Release of the bail handle results in the spring force initiating engagement of a safety mechanism which can include a brake and/or clutch to stop rotation of the engine, the rotating implement, or both. The electrical ignition system of the engine is also often defeated.
Because the spring force against which the bail handle or other deadman safety lever acts is relatively strong, a Bowden cable of the type in which the inner wire acts only in tension is most commonly employed for transmitting force from the safety lever to the safety mechanism. Consequently, regardless of the arrangement of the safety brake or clutch as it attaches to the engine, it is best actuated by a pulling movement of the inner wire of a Bowden cable relative to its sheath which is fixed to the engine or to some other structure fixed relative to the engine. Alternately, the inner wire of the Bowden cable could be fixed and the sheath could provide a pushing motive force, which would still allow the inner wire to be active in tension. This alternative is not satisfactory, however, since free movement of the sheath is liable to be impaired by interference from the engine, lawn mower handle, or other incidentally adjacent structure, thus degrading the reliability of the deadman safety device.
The most straightforward arrangement of a Bowden cable acting in tension when utilized on a walk behind implement is one in which the cable runs downwardly from the handle grip and approaches the engine from the rear of the implement. Thus, the cable is suited for exerting a rearward pulling force. It is easy enough to then provide suitable linkage to connect the Bowden cable to the device for disengaging the safety brake, assuming the orientation of the engine and its brake mechanism are known. However, manufacturers of lawn mowers sometimes prefer to orient the engine such that the cylinder faces forward and other times prefer to orient the engine such that the cylinder faces rearward. Since the linkage for disengaging the safety brake is associated with the engine itself, it would be desirable to provide such a linkage which could accommodate either orientation cf the engine as desired by the mower manufacturer and yet allow the connection to the Bowden cable to be a mere matter of alternative assembly without requiring parts changes. This present invention provides such a linkage arrangement.